Method for forming a tap hole in a wall portion of a metallurgical furnace containing molten metal



Jan.' 27, 1970 w. REscH ET AL METHOD FOR FORMING A TAP HOLE IN A WALLPORTION OF A METALLURGICAL FU Original Filed June 9. 1966 RNACECONTAINING MOLTEN METAL 5 Sheets-Sheet 1 r ww V.. IHM? Jan.' 27,1970 w.RescH am 314A9z,1.11

NACE CONTAINING MOLTEN METAL METHOD FOR FORM-ING 4A TAP HOLE IN A WALLPORTION METALLURGICAL FUR Original Filed June 9. 1966 3 .Sheets-Sheet 2WEA/7a? 'Jem/En @asm Jan. 27, 1970 w. RSCH rAL 3,492,171 METHOD FoaFORMING A TAP HOLE IN A WALL PORTION oF A METALLURGICAL FURNAE CONTAINIGMOLTEN METAL Origlnal Filed June 9. 1966 5 Sheets-Sheet 5 @um Flegg 472,um L JM.

Mrw() United States Patent O Int. c1. Bzsk 7/00 U.S. Cl. 148-9 7 ClaimsABSTRACT OF THE DISCLOSURE A method of forming a tap hole in a wallportion of a metallurgical furnace in which the tap hole is prebored toa predetermined depth by mechanical boring means and in which theremainder of the tap hole is burned through by means of an oxygenblowpipe.

CROSS REFERENCE TO RELATED APPLICATIONS The present application is adivisional application of the application tiled with the Ser. No.556,506 on June 9, 196'6, now Patent No. 3,450,399.

BACKGROUND OF THE INVENTION The present invention relates to a methodfor forming a tap hole in a wall of a metallurgical furnace containingmolten metal.

In known methods of this type, the. tap hole is prebored to apredetermined depth either by hand or by an appropriate boring machineand the remainder f the tap hole is burned through by means of an oxygenblowpipe.

In carrying out this method as known in the art, the operator handlingthe blowpipe has to stand laterally of the tap hole and at aconsiderable distance from the outer end thereof so that it is extremelydifficult for him to guide the blowpipe coaxial with the preboredportion of the tap hole. This may result that the final portion of thetap hole will be located inclined to the theoretical axis thereof, whichin turn may result in damage of the wall portion of the furnace aboutthe tap hole by the hot molten metal emanating therefrom. In additionthere iS the danger that the blowpipe is introduced too far ntO thefurnace in direction inclined to the axis of the tap hole so that damageof the furnace wall about the tap hole during the burning operation mayresult. In carrying out such a method there is also always the dangerthat the operator may be'injured by the stream of molten metal emanatingfrom the opened tap hole, especially when the stream of metal impingeson the blow pipe.

In order to overcome these disadvantages, methods and boring apparatushave already been developed in which opening of the tap hole is carriedout only by mechanical means, which may even be remotely controlled, sothat the tap hole will always be formed over its whole length at thesaine exactly adjusted angle. The forming of the tap hole is in thiscase carried out in two steps, in the first step the tap hole is boredout to a predetermined depth, whereas during the second Step theremainder of the tap hole is formed by a percussion drill.

This known method is not very well suited for the forming of tap holesin open hearth furnaces, especially in Siemens-Martins ovens, since insuch furnaces the final opening of the tap hole is in the most casesonly possible by means of an oxygen blowpipe. The aforementioned methodhas also the disadvantage that the second tool has to be moved, afterthe tap hole has been completely opened and the molten steel emanates ina stream therefrom, at least through the length of the tap hole indirection of the emanating stream of molten steel and that only afterthe second tool has been withdrawn in this direction, the whole machinemay be moved in direction transverse to the stream of emanating steelout of the iniluence of the latter. During the time of withdrawal of thesecond tool in axial direction the machine is subjected to the influenceof the hot molten steel emanating from the opened tap hole so thatdamage to the tool and to the machine are hardly avoidable and so thatreplacement of the second tool and/or repair of the machine will becomenecessary after only a few operations.

This known method has therefore also not worked out to fullsatisfaction, especially since in modern furnaces the period betweensuccessive tappings of the furnaces are considerably reduced so thatmethods and apparatus for forming the tap holes without damage to theapparatus become of increasing importance.

It is an object of the present invention to provide for a method forforming tap holes in a furnace which avoids the above-mentioneddisadvantages of methods known in the art.

It is an additional object of the present invention to provide for amethod for forming tap holes in a furnace in which the danger ofdamaging the apparatus carrying out the method by the hot metalemanating from the tap hole is reduced to a minimum.

It is a further object of the present invention to provide a method forforming a tap hole in a furnace by pre-boring the tap hole rst to apredetermined depth and by burning out the remainder of the tap hole byan oxygen blowpipe and in which the appartus may be moved in directiontransverse to the stream of hot metal at the moment the hot metalemanates from the furnace.

SUMMARY OF THE INVENTION With these objects in view, the methodaccording to the present invention for forming a tap hole in a wallportion of a metallurgical furnace containing molten metal, mainlycomprises the steps of advancing a boring tool in a predetermineddirection against the wall portion of the furnace for boring a tap holeto a predetermined depth in the wall portion, retracting the boring toolout of the bored wall portion, advancing a blowpipe in said directionthrough the prebored portion of the tap hole, burning through theremainder of the wall portion by means of oxygen blown through theblowpipe, and cutting off the front portion of the blowpipe at themoment of finishing the tap hole to the full depth thereof and dischargeof molten metal through the opened tap hole from the furnace, so that acommon carrier mounting the boring tool and the blowpipe may be moved ina direction transverse to the path of molten metal emanating from thefurnace at the moment of cut-off of the front portion of the blowpipe.This method will assure that the complete tap hole will extend throughthe wall portion of the furnace in the predetermined direction and themethod has the further advantage that the carrier which carries theboring tool and the blowpipe may be removed out of the danger zone atthe exact moment at which the molten metal emanates from the furnace.The cost of the cut-olf portion of the blowpipe is negligible ascompared to the advantages derivable from this method which will assurethat damage to the remainder of the apparatus during repeated operationsis completely avoided. Preferably, the method includes also the step ofsensing discharge of molten metal from the opened tap hole 3 andautomatically controlling cut-off of the end portion of the blowpipe andmovement of the common carrier in dependence on the sensed discharge ofmolten metal from the furnace.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. l is a schematic partly sectionedside view of the apparatus of the present invention as mounted on ametallurgical furnace only partly shown in FIG. l;

FIG. 2 is a front View of the apparatus shown in FIG. 1, with someelements of the apparatus removed for the sake of clarity; and

FIG. 3 is a longitudinal cross section through part of the apparatusshown in FIG. 1 drawn to an enlarged scale and showing the boring meansin the retracted position thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings,and more specifically to FIGS. l and 2 of the same, it will be seen thatthe apparatus according to the present invention comprises support meanswhich preferably include a carriage 3 movably guided by means of rollers3a in a pair of U-shaped guide rails 2 extending in substantiallyhorizontal direction and being mounted in any convenient manner on aportion of a furnace 1, only partly and schematically illustrated inFIG. 1. The support means include further elongated guide means in formof a pair of tubular members 5 projecting spaced from and parallel toeach other downwardly from a bottom wall of the carriage 3 and beingconnected at the upper ends thereof in any convenient manner, forinstance by welding, to the latter. A pair of guide sleeves 5a arearranged spaced from each other on each of the tubular guide members 5and the guide sleeves 5a are connected by cross bars 5b to an additionaltubular member 6 located midway between the pair of tubular members 5and extending with a lower portion thereof downwardly beyond the lowerends of the tubular members 5, as best shown in FIG. 2. A plug 6a isfixed, for instance by welding, in the lower portion of the tubularmember 6, extending with a bottom portion thereof beyond the bottom endof the tubular member and this bottom portion is preferably of square orrectangular cross section. The bottom portion of the plug 6a is formedwith a bore extending transverse to the axis of the tubular member 6 anda working head 9 having a pair of side walls 9 and 9" is tiltablymounted on the bottom portion of the plug 6a by means of a pin 6bextending through the aforementioned bore. Each of the side walls of theworking head 9 is formed with a curved slot 9a substantially coaxial tothe axis of the pin 6b through which screw bolts 9b ixed to the plug 6aextend so that nuts screwed onto opposite ends of the screw bolts may beused for fixing the working head 9 in a desired angular position withrespect to the axis of the tubular member 6.

The working head 9 carries between the side walls 9' and 9" thereofelongated boring means movable in axial direction and rotatable aboutits axis. The elongated boring means comprise, as best shown in FIG. 3,an elongated tubular member 24 guided for movement in axial directionbetween a plurality of lower guide rolls 24a and an upper guide roll 24bturnably mounted between the side walls of the working head 9. Coaxiallyarranged within the tubular member 24 and turnable about its axisrelative thereto is an elongated tubular boring member 17 formed at thefront portion thereof facing the furnace 1 with appropriate cuttingportions. During the actual boring operation, the front end of thetubular boring tool 17 is closed by plug 18 removably inserted in thefront end thereof. The tubular boring member 17 is rotated about itsaxis by means of a motor 19 iixedly mounted on the rear end of thetubular member 24 and connected to the rear end of the boring tool 17 bymeans of a reduction gearing 20. The motor 19 is preferably a motor ofknown construction operated by compressed air. The tubular member 24 andthe tubular boring tool 17 mounted therein for movement in axialdirection therewith are advanced in axial direction by means of a rack25 iixed to an upper portion of the tubular member 24 and meshing with apinion 23 which is mounted on a rocker arm 22 pivoted at a front endthereof at 22 to the side walls of the working head 9 and carrying atthe other end thereof a motor 21 of known construction, preferablydriven by compressed air and connected to the pinion 23 by means of abelt or chain drive 21a so as to rotate the latter.

An elongated blowpiece 26 extendsy substantially coaxial through theinterior of the tubular boring tool 17 and is slidably guided thereinfor movement in axial direction so that the front portion of theblowpipe 26 may, after the plug 18 is removed from the tubular boringtool 17, project beyond the front end of the latter. When the blowpipe26 is formed from a substantially rigid tube, the latter may be moved inaxial direction relative to the tubular boring tool 17 by means of anannular piston 27 fixed to a rear portion of the blow pipe and bycompressed air acting on the piston 27.

On the other hand, the blowpipe may be formed from flexible tubing andthe rear portion thereof may be wound on a spool and in this case theblowpipe may be advanced by turning the spool about its axis.

The apparatus includes further cutoff means for cutting off the portionof the blowpipe 26 projecting beyond the front end of the boring means24, 17 when the latter are in the retracted position as shown in FIG. 3.The cutoff means include a cutoff knife 13, guided between a pair ofguide plates 12 extending spaced from each other and transverse to theside plates of the working head 9, and being movable between a retractedposition, as shown in FIG. 3, in which the cutting edge 14 of thecutting knife 13 is upwardly spaced from the tubular member 24 and acutoff position in which the cutting edge 14 cuts through the endportion of the blow pipe 26 when the latter projects beyond the frontend of the tubular member 24 through the guide plates 12. The cutoffknife 13 is moved between the positions thereof by operating meansincluding cylinder and piston means 15 operated by compressed air andincluding a cylinder 15a pivotally mounted at one end thereof on theworking head 9 and a piston 15b slidably guided in the cylinder 15a andhaving a piston rod projecting be yond the other end of the cylinder 15aand being pivotally connected to a plate-shaped lever 16 which in turnis pivotally mounted in the manner as best shown in FIG. 3 on theworking head 9. The end of the lever 16 distant from the end connectedto the piston rod of the piston 15b is connected by means of a pin andslot connection to the upper end of the cutoff knife 13, as shown inFIG. 3'. The cylinder and piston means 15 may also include a compressionspring 15c mounted between the other end of the cylinder 15a and piston15b in the manner as shown in FIG. 3 and being biased in such a mannerso as to yieldably maintain the cutoff knife 13 in the retractedposition as shown in FIG. 3. A tube or hose 15d, communicating with theinterior of the cylinder 15a in the manner as shown in FIG. 3, serves tofeed compressed air into the cylinder so as to move the piston 15bagainst the force of the compression spring 15e towards the left, asviewed in FIG. 3, to move thereby the cutoff knife 13 from the retractedto the cutoff position thereof. A valve 28 in the tube 15d controls owof compressed air into and out of the cylinder 15a.

Biasing means are connected to be working head 9 for moving the latterfrom a working position in which the boring means 24, 17 are alignedwith a portion of the furnace in which the tap hole is to be formed andan inactive positon in which the working head is displaced in directiontransverse to the axis of the boring means from the working positon. Thebiasing means may include a pair of elongated weights 7 slidably guidedin the tubular members 5 and connected by ropes 7a or the like to thetransverse bars 5b which connect the guide sleeves 5a to each other. Theropes 7a are preferably guided over rollers 7b turnably carried by thecarriage 3, as best shown in FIG. 2. 4The biasing means may also includea coil tension spring 8 xed. at opposite ends thereof to the carriage 3and the upper end of the tubular member 6, which supports the action ofthe weights 7. Likewise, a weight 4 connected by means of a rope 4a orthe like and guided over a roller 4b turnably mounted on the guide rails2 is connected to thefarriage 3 so as to tend to move the latter inlateral direction so as to move the parts of the apparatus connected tothe carriage 3 in horizontal direction away from a position in which theboring tool carried by the working head 9 is properly located withrespect to the furnace 1.

The apparatus includes further locking means cooperating with the guidemeans or guide sleeves 5a and with the carriage 3 for maintaining theguide sleeves 5a and the part of the apparatus connected thereto as wellas the carriage 3 against the forceexerted by the biasing means, that isthe weights 7 and 4 and the spring 8 in a position in which the boringmeans carried by the working head of the apparatus are properly alignedwith a predetermined Wall portion of the furnace. The looking means mayinclude a locking pin 29 extending through appropriate aligned bores ofone of the sleeves 5a and the corresponding tubular member 5 andmoveable between a locking position as shown in FIG. 2 and a releasingposition in which the pin 29 is removed from the bore in the tubularmember 5 so that the sleeve 5a is free to move in upward direction underthe influence of the biasing means connected thereto, The locking pin 29is connected by a pin and slot connection to the upper end of a lever 30pivotally connected yat a lower end to a lower portion of the tubular`vmember 5 and moved from the locking position to a releasing positionin which the pin 29 is withdrawn from the bore in the member 5 by meansof a rope 31 or the like which is guided over a roller 32 mounted on-the working head 9 and connected at the end opposite from the lever 30to a lever 33 which is xed to the plate-shaped lever 16 for turning withthe latter. A spring 34 connected to the lever 30 tends to maintain thelocking pin 29 in the locking position thereof. A rope 35 or the likeconnects the lever 30 to an additional locking pin 36 projecting in thepath of the carriage 3 to engage the left end of the path of thecarriage 3 to engage the `left end of the latter, as viewed in FIG. 2,to prevent movement of the carriage 3 to the left, as viewed in FIG. 2,under the inuence of the weight 4. A spring 37 cooperates with thelocking pin 36 tending to maintain the latter in the locking position asshown in FIG. 2. y

The apparatus may further include sensing means 38 of known constructionarranged in the region of the wall portion of the furnace 1 in which thetap hole 10 is to be formed for sensing hot metal emanating from the taphole. The sensing means may be lin' the form of an electric eye or inthe form of temperature sensing means and the specific construction ofthe sensing means used does not form part of the present invention. Thesensing means have to be constructed in such a manner so as toinstantaneously sense when hot molten metal emanates from the tap hole10. The sensing means 36 are connected in a known manner to the valve 28to open the latter for feeding compressed air into the cylinder 15a soas to move the piston 15b in a direction which moves the cutting knife13 from the retracted to the cutoff position thereof at the moment hotmolten metal emanates from the finished tap hole.

The operation of the apparatus above described will be obvious from thedescription thereof. The angular position of the working head 9 relativeto the tubular support thereof is first adjusted by means of theadjusting means 9a, 9b above-described, and the locking pins 29 and 36are maintained in the engaged position so that the boring means 24, 17are properly aligned with the wall portion of the furnace 1 in which thetap hole 10 has to be formed. The tubular boring member 17 is thenrotated about its axis by means of the motor 19 and the tubular member24 as well as the tubular boring tool 17 are advanced'from the positionshown in FIG. 3 so as to engage a wall portion of the furnace 1 in whichthe tap hole 10 is to be formed and to bore this tap hole to apredetermined depth. The boring means 24, 17 are then retraced, byreversing the motor 21 in a known manner, again to the position shown inFIG. 3 and the plug 18 is removed from the front end of the tubularmember 17. The blowpipe 26 is then advanced from the position shown inFIG. 3 to extend through the guide plates 12 and into the preboredportion of the tap hole 10 and the remainder of the tap hole is thenburned out by feeding oxygen through the blowpipe 26. When the tap hole10 is completely opened molten metal in the furnace will emanatetherethrough, and the sensing means 38 will sense emanation of moltenmetal from the tap hole. The sensing means 38, when energized, will openthe valve 28 so that the piston 15b is moved from the position shown inFIG. 3 to a position in which the cutoff knife 13 is moved in downwarddirection to cut off the portion of the blowpipe 26 extending beyond theright guide plate, as viewed in FIG. 3. During the movement of thepiston 15b towards the left, as viewed in FIG. 3, the lever 33 connectedto the lever 16 will turn in counterclockwise direction moving therebythe locking pins 29 and 36 to the releasing position so that the workinghead 9 is moved under the influence of the biasing means, that is theweights 7 and the spring 8, in upward direction, whereas the carriage 3is moved under the influence of the weight 4 towards the left, as viewedin FIG. 2, so that the apparatus is vertically and horizontally movedrelative to the stream of molten metal emanating from the tap hole 10.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofmethods for forming a tap hole in a Wall portion of a metallurgicalfurnace differing from the types described above.

While the invention has been illustrated and described as embodied in amethod for forming a tap hole by preboring the tap hole to apredetermined depth and by burning out the remainder of the tap hole, itis not intended to be limited to the details shown, since variousmodifications and structural changes may be made without departing inany way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this invention.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims:

1. A method of forming a tap hole in a wall portion of a metallurgicalfurnace containing molten metal, comprising the steps of advancing aboring tool in a predetermined direction against the wall portion of thefurnace for boring a tap hole to a predetermined depth in said wallportion; retracting the boring tool out of the bored wall portion;advancing a blowpipe in said direction through the prebored wallportion; burning through the remainder of the wall portion by means ofoxygen blown through the blowpipe; and cutting off the front portion ofthe blowpipe at the moment of finishing the tap hole to the full depththereof and discharge of molten metal through the opened tap hole fromthe furnace.

2. A method as set forth in claim 1 and including the step of mountingsaid boring tool and said blowpipe on a common carrier, and moving saidcommon carrier out of the path of the molten metal emanating from thefurnace at the moment of cutoff of the front portion of said blowpipe.

3. A method as set forth in claim 2, lwherein said common carrier ismoved in vertical and horizontal direction out of the path of the streamof metal emanating from the furnace.

4. A method as set forth in claim 3, and including the step of sensingdischarge of molten metal from the opened v tap hole and automaticallycontrolling the cutoff of the end portion of the blowpipe and movementof said common carrier in dependence on the sensed discharge of moltenmetal.

5. A method as set forth in claim 1, wherein said boring tool is tubularand wherein said blowpipe is advanced through said tubular boring tool.

6. A method as set forth in claim 5, wherein said front portion of saidblowpipe is cut off in the region of the front end of saidfboring tool.

7. A method as set forth in claim 1, wherein the step of cutting offsaid front portion of said blowpipe is carried out by moving a cuttingknife transverse to the axis of said blowpipe.

References Cited UNITED STATES PATENTSA 1,872,410 8/1932 Coberly 148-9L. DEWAYNE RUTLEDGE, Primary Examiner W. W. STALLARD, Assistant Examiner

